Rotary fan



Sept. 9 19241- 1,508,086

R. F. CRAWFORD ROTARY LFAN Filed July 2. 1923 Patented Sept. 9, 1924.

U l T E f isa-aast RALPH F. CRAWFORD, 0F SALINA, KANSAS.

ROTARY FAN.

Application filed July 2,

'To all whom z't may concer/1,.'

Be it known that I, RALPH F. CRAWFORD, a citizen of the United States, residing at Salina, in the county of Saline and State of Kansas, have made a certain new and useful Invention in Rotary Fans, of which the following is a specification.

The invention relates to rotaryv fans, designed to throw a column of air in a given direction, for purposes of cooling, ventilating or wherever a fan would be useful, and also for purposes of propulsion, the object being to increase the efficiency or to displace a maximum volume of air for a 'given size of fan, power applied, and speed of rotation.

The invention consists in the novel construction and combinations of parts, as' hereinafter set forth.

In the accompanying drawings illustrating an embodiment of the invention, the numerals l, 1, designatethe radial blades of the fan or propeller, joined by a cent-ral plate 2 or other hub member. As shown, the complete fan or propeller comprises two sheet metal portions, each consisting 'of opposite blades 1, l, and a plate 2, perforated at 3 for securing screws, whereby the fan or propeller may be mounted upon a shaft.

In cross section, each blade is formed with a forward edge portion 4, disposed at an angle (60 degrees as shown) from the axial line o-f the fan; a middle portion 5 preferably disposed at a higher angle from said axial line (75 degrees as shown), and a rear portion 6, having a major part thereof disposed in an arc of approximately 75 degrecs, and ending preferably in a short marginal part 7, lying parallel with said axial line; The forward and middle portions 4 and 5 comprise each approximately one-fourth of the blade,l and the rear portion 6 one-half thereof.

In operation, the forward edge portion 4 of the fan blade is designed to feed air to the blade pocket formed by the portions 5 and 6, by the latter of which said air will be thrown rearwardly to be utilized as desired.

It is found in practice that a fan made as stated will show considerably greater eili- 'ciency than fans of common commercial type, such for instance as the propeller type fans used in automobile engine cooling sys- 1923. Serial No. 649,072.

tems. It is further found. in practice that thls fan may be driven with an unusually loose belt, considering the pressure of air displacement.

The forward portion 4 of the respective blades may be varied from approximately the angle shown in Figure 3 in full lines to the dotted line showing'of said portion 4 1n line with 'the middle portion 5. The forward and middle portions 4 and 5 when so 1n line or in theA same plane constitute together a 'forward portion of the blade equal 1n extentor area to the rear portion 6 of the blade.

I claim:

1. In a rotary fan, radial blades having each a forward portion having an angular relation to the axial line of the fan, and a rear portion including the balance of the bladel and approximately equal in extent to said forward portion and having the major part thereof disposed inan arc subtending an angle equal to that subtended by said forward portion and said axial line.

2. In a rotary fan, radial blades having each a forward ortion having an angular relation to the axial line of the fan, a middle portion having a higher angular relation to said line, and a rear portion approximately equal in extent to said forward and middle portions and :disposed in an arc.

3. In a rotary fan, radial blades having each a forward portion having-an angular relation to the axial line of the fan, a middle portion having a higher angular rela' tion to said line, and a rear portion approximately equal in extent to said forward and middle portions and disposed in an arc subtending an angle equal to that subtended byl said middle portion and said axial line.

4. In a rotary fan, radial blades having each a forward portion having an angular relation to the axial line of the fan of approximately 60 degrees, a middle portion aving a higher angular relation to said line of approximately 75 degrees, and a rear portion approximately equal in extent to said forward and middle portions and disposed in an arc subtending an angle of approximately-75 degrees.

l In testimony whereof I affix my signature.

RALPH F. CRAWFORD. 

